Control device for a heat transfer system



Sepit 18, 1934 W. B. NORMELLI CONTROL DEVICE FOR A HEAT TRANSFER SYSTEM Filed. Dec. 16. 1952 5 Sheets-Sheet 1 Sept. 18, 1934.

w. B. NORMELLI 1,974,121

CONTROL DEVICE FOR A HE AT TRANSFER SYSTEM 7 5 SheecLs-Sheet 2 Filed Dc. 1a. 1932 Sept. 18, 1934- w. B. NORMELLI CONTROL DEVICE FOR A HEAT TRANSFER SYSTEM Filed Dec. 16. 1952 s Sheets-Sheet a A I I z I l Patented Sept. 18, 1934 PATENT CONTROL DEVICE FOR A HEAT TRANS SYSTEM Wulfl' Berzelius Normelli, Berlin-Gharlottenbnrg,

Application December 10, 1932, Serial No. 647,668

Germany December 19, 1931 s (on. 62-5) My invention relates to a control device for a heat transfer system in which an alternately evaporating and condensing liquid is employed as circulating medium. The object of my invention is to provide a control device in a heat transfer system of the above-indicated character so as to control the circulation of liquid without the use of valves. To this end, I provide an overflow and connect according to the invention the overflow to a storage tank designed in such a manner as to take up the total amount of liquefied circulating liquid. For controlling the circulation of liquid, and consequently the transfer of heat, the relative height of the liquid level in the store age tank is varied with respect to said overflow. The inventive idea may be realized by providing a flexible overflow which may be adjusted with respect to a fixed liquid level in the storage tank. Reversely, it is also possible to raise or lower the level of the liquid in the storage tank with respect to a fixed overflow connected tothe storage tank. Furthermore, the last two-mentioned cases may also be, for instance, combined by pivotally mounting the storage tank at a fixed point. In order to raise or to lower the level of the liquid with respect to a fixed overflow, the volume of the storage tank is varied below the point at which the overflow takes place by means of elastic walls, (bellows or the like) or by means of a control liquid as well as by a mechanically operated fluid displacer and similar means. The raising or lowering of the liquid level in the storage tank may be carried out in the above-mentioned cases by hand. However, it is also possible and in many cases'preferable to employ a control member for adjusting the liquid level automatically.

The invention may be applied to advantage to heat transfer systems which are used for a variety {0 of p p ses; for instance, to give up the heat available in a cooling chamber to a colder medium for producing refrigeration or to transfer heat from a source of heat; for instance, a steam boiler to a chamber to be heated. The invention is equally applicable to a system for the transfer of heat, which serves to give up heat of absorp-- tion of an absorption refrigerating apparatus of the intermittent type to a cooling medium; for

instance, water or to the surrounding atmosphere.

For controlling the circulation of liquid in accordance with the temperature prevailing in a chamber, a gas or liquid thermometer is preferably employed as control member in which changes in the volume are caused by variations of temperature prevailing in the chamber. In this manner, it'is possible to provide a simple device which controls in heating systems the supply of heat in accordance with the temperature of the space to be heated and in cooling systems the transfer of heat in accordance with the temperature of the cooling chamber.

In the accompanying drawings some embodiments of my invention are illustrated diagrammatically.

Fig. 1 shows diagrammatically a heat transfer system which serves to transfer the cold fluid stored in a storage tank to a cooling chamber and thereby abstract heat from said cooling chamber;

Fig. 2 shows diagrammatically a similar heat transfer system as disclosed in Fig. 1;

Fig. 3 shows a system in a diagrammatic form which serves to transfer the heat produced by a steam boiler to a chamber;

Fig. 4 shows diagrammatically an embodiment of my invention as applied to an absorption apparatus of the intermittent type in which a device serves to indirectly cool the absorber-generator, and

Fig. 5 shows another embodiment for the heat transfer devices of an absorber-generator as may be employed in place of the embodiment shown in Fig. 4.

In Fig. 1 is shown a transfer system which serves to transfer the refrigeration stored in a cold accumulator 2 of a refrigerator to a cooling chamber 3 insuiated from said accumulator 2. The refrigeration produced in the accumulator 2 for the above purpose may be supplied in any form whatever. To this end, Fig. 1 discloses an evaporator coil 1 of a refrigerating apparatus (not shown), a fluid being contained in said'accumulator which freezes upon the evaporation of the refrigerating medium. However, the" accumulator may also .be charged with ice, brine ice, carbonic anhydrid snow, freezing mixtures or the like. The condenser 4 for the circulating system is disclosed in the accumulator 2. A storage tank 5 for the reception of the circulating liquid is connected to the condenser 4 through a conduit 6. An overflow conduit '7 through which the liquid circulating medium reaches an evaporator coil 8 located in the cooling chamber 3 is connected to the top of the storage tank'5. The evaporation of the circulating medium causes a low temperature in the cooling chamber 3 which produces refrigeration. This vapor then passes through a conduit 9 into the condenser 4 which to assist the dissipation of heat is provided with cooling ribs 19. The vapor condenses in the condenser 4 and the liquefied medium flows through the pipe 6 into the storage tank 5. The latter is so designed that it'may take up the entire auxiliary liquid for the transfer of heat at a predetermined lowest temperature in the cooling chamber 3 so that the auxiliary liquid cannot flow again to the evaporator through the conduit '7.

For controlling the transfer of heat, a gas thermometer 10 as control member is arranged in the cooling chamber, the thermometer being connected to a closed container 12 through a conduit 11. The container 12 is secured to the storage tank 5 and is provided with a bellows 13. By reason of the fluctuations of temperature in the cooling chamber, corresponding variations of volume are brought about in the gas thermometer.

The changes in volume cause in the cooling chamber an expansion of the bellows 13 upon a rise of temperature, thereby decreasing the volume of the tank 5 and eflfecting an overflow of the circulating liquid. Reversely, a drop in temperature causes a contraction of the bellows 13 and, therefore, such an increase in volume of the storage tank 5 as to prevent an overflow of the circulating liquid. It is particularly advantageous to render the surface of the circulating liquid so small that the liquid, as a result of small changes in volume brought about by the control memberlO, is caused to overflow or prevented from overflowing. In the embodiment shown in Fig. 1, the storage tank 5 is for this purpose dimensioned in such a manner that the liquid contained in the conduit 6 and in the overflow conduit '7 reaches the level shown in Fig. 1.

If a refrigeration is to be produced in the cooling chamber as a result of a rise in temperature in said chamber, the liquid is caused to circulate in the above-described manner. Should the temperature drop to a sufliciently low value, the control device immediately interrupts the circulation and, consequently, a cooling eflect is no longer obtained.

'It is advisable that the control device be of the adjustable type in order to adjust the operating temperature for. the system of transfer to any desired value. For this purpose, the gas thermometer 10 is provided with a bellows 21 adjustable by a screw 20.

Fig. 2 discloses a similar embodiment of my invention, like numerals of reference denoting like parts. The control member 14 arranged in the cooling chamber 3 is in this case of the liquid type. It operates with a control liquid, whose specific gravity is heavier than that of the circulating liquid; for instance, mercury. The level of thecirculating liquid in the conduits is directly adjusted in this case by the changes in volume of the control liquid. Upon a rise in temperature, the control liquid contained in the control member 14 forces the circulating liquid through the conduits 15 and 16 in an upward direction, and, therefore, displaces a portion of the circulating liquid from storage tank 5, so that the liquid in the conduits 6 and '7 rises and at a predetermined temperature passes from theoverflow conduit 7 into the evaporator 8 so as to cause as in the case ofFig. 1 a transfer of heat from chamber 3 to chamber 2. The control member 1415 pro-.

vided with a movable bellows 1'? which may be adjusted by a screw 18.

The individual parts of apparatus are in Fig.

2 so designed and arranged that the heavier control liquid may easily fiow back into its container, if the mercury during the transport should have reached other parts of the refrigerator. To attain this, the apparatus need only be at first tilted to the right and then placed in the vertical position. The conduit 16 serves to ensure the escape of the circulating liquid or of the gas from the container 14 that might have reached the container 14 during the transport.

An embodiment of my invention as applied to heating systems is shown in Fig. 3. In the latter is disclosed a system for the transfer of heat which serves to heat a chamber 21. The supply of heat takes place from a steam boiler 22 in the dome of which an evaporator coil 23 is located. From the upper part of the evaporator coil 23, a

conduit 24 leads to a condenser 25 designed as radiator and arranged in a space 21 to be heated. To the opposite end of the condenser 25 a conduit 26 is connected which leads to a storage tank 28 pivotally mounted as indicated at 2'7. An pverflow conduit 29 connected to thelower end of the evaporator coil 23 is connected to the tank 28. For controlling the transfer of heat a rod 30 responsive to changes of temperature is employed whose elongation is a measure for the temperature of the space. The rod 30 engages the storage tank 28 through a lifting mechanism in such a manner that it may raise or lower the container 28 corresponding to the temperature prevailing in the chamber 21. In order to ensure the niove ment of the storage tank 28 part of the conduit 26 entering the storage tank 28 and part of the return conduit 29 must be of the flexible type. The storage tank 28 is so dimensioned as to take up the total liquid required for the transfer of heat. The temperature responsive rod 30 controlling the storage tank 28 is then adjusted in such a manner that the liquid level in the tank 28 at a desired temperature of the chamber 21 is below the overflow 31 so as to prevent the liquid from reaching the evaporator 23 through the overflow conduit 29. In the position of the tank shown in Fig. 3 no transfer of heat, consequently, takes place. If the temperature in the chamber 21 should drop, the storage tank 28 will be rotated in counter-clockwise direction as a result of the contraction of the rod caused by the drop in temperature, so that the liquid may reach the evaporator 23 through the overflow conduit 29. By the heat supplied to the evaporator 23 the liquid will evaporate. The vapors pass through the rising conduit 24 into the condenser 25 where upon liquefy-.

ing they give up their heat of condensation. The liquid circulating medium then flows through the conduit 26 back into the storage tank 28.

Fig. 4 shows an application of my invention for a system of the transfer of heat which serves to transfer the heat of absorption of an absorption refrigerating apparatus of the intermittent type pors are liquefied in the condenser 43 and the' liquid ammonia flows into an intermediate vessel 44 surrounded by the insulation of the refrigerator. An evaporator coil 45 projecting into the cooling chamber 46 is connected with the vessel 44.

The absorber-generator 41 is surrounded by a heat-insulated jacket 47. At the upper part of the jacket a conduit 48 is connected which leads' to an air-cooled condenser 49 disposed above the refrigerator. The other end of the condenser 49 enters the upper part of a storage tank 59 which contains the circulating medium, for instance, water. A return conduit 51 is connected to the central portion of the storage tank 50 and returns to the lower part of the absorber-generator jacket 47.

A fluid displacer 52 which may be controlled by means of an electromagnet through a coil 57 in accordance with the clock switch 55 is arranged in the storage tank 50. During the heating period the electromagnet is energized, thereby causing the displacer 52 to move upwardly to the position shown in the Fig. 4, and the total amount of the auxiliary liquid contained in the above-said system for transfer of heat is thus permitted to collect in the storage tank 50. The conduit 51 is connected to the storage tank 50 at such a high point so that, when the displacer is removed from the liquid, the liquid cannot overflow intothe conduit 51. During the absorption period, the

clock switch 55 disconnects the electromagnet 53,

circulating medium passing through the conduit 48 and liquefying in the condenser 49 flows back to the storage tank 50 and the circulation is repeated as above described. By cooling the absorber-generator, the absorbent is again capable.

of absorbing the refrigeratingmedium so that the ammonia evaporates in the coil 45 and returns to the absorber-generator 41. The evaporation of ammonia results in a low temperature which produces refrigeration.

With the aid of' this device, it is possible to maintain in a simple manner also the temperature of the cooling chamber to a desired value. To this end, a thermostat 59 is located in the cooling chamber 46. When the temperature of the cooling chamber drops below a predetermined low value, the contact of the thermostat 59 closes, thus connecting a coil 53 to the supply circuit 56.

In this case, the liquid displacer also moves in an upward direction so that no liquid flows back into the absorber-generator jacket. The circulation of the auxiliary medium for transferring the heat of absorption is thereby interrupted so that no ammonia is absorbed, thus also interrupting a further production of refrigeration in the cooling chamber 46. If the temperature of the cooling chamber should rise again above the operating value of the thermostat, the contact of the latter opens and the liquid displacer dips into the liquid so as to cause a transfer of heat and a subsequent production of refrigeration.

Instead of an absorber-generator as described in Fig. 4 an arrangement as shown in Fig. 5 may also be employed to advantage. In this case the vertical generator 41 is provided on the outer jacket with troughs 58 in which the cooling liquid trickling from the storage tank 50 through the conduit 51 in a downward direction is collected so that on coming into contact with the parts ofthe absorber-generator the liquid evaporates. The vapor then passes from the heat insulated jacket 47 through a conduit 48 connected to the upper end thereof into the condenser 49 in a similar manner as disclosed in the embodiment of Fig. 4. Instead of the displacer shown in Fig. 4 one of the control members shown in the other embodiments may also be employed in a corresponding manner. The control member may, for instance, be so designed as to be heated by a special heating device which is inserted when the heat of the generator is cut off so that a circulation is also brought about in this case by means of a change in volume in the control medium; for instance, by means of a change in volume of a gas corresponding to Fig. 1 or of a liquid corresponding to Fig. 2.

I claim as my invention:-

1. A system for the transfer of heat, in which an auxiliary liquid is maintained in circulation by alternate evaporation and condensation, a storage tank for the reception of the said liquefied auxiliary medium, an overflow rigidly connected to said storage tank, a bellows connected with said storage tank, and means for causing said bellows to change the level of said liquid contained in said storage tank.

2. In a system for the transfer of heat in which an auxiliary liquid is maintained in circulation by alternate evaporation and condensation, a storage tank for the reception of the liquefied auxiliary medium, an overflow connected to said storage tank, a control member for changing the level of said liquid contained in said storage tank, said control member being associated with said storage tank, and a control liquid contained in said control member.

3. A system for transferring heat from a warm space to a cold space by means of a circulating fluid, comprising an evaporator arranged in said warm space, a .condenser in said' cold space, means for circulating the fluid between said evaporator and said condenser, containing a storage tank for the circulating medium in said cold space, an overflow connected to said storage tank, and control means for varying the height of the liquid level with respect to said overflow, said control means operating in accordance with the temperature prevailing in one of said spaces so as to cause an automatic circulation or interruption of the liquid.

WULFF BERZELIUS NORMELLI. 

